1. Technical Field of the Invention
The present invention relates to novel cosmetic and/or dermatological compositions (hereinafter sometimes "antisun" or "sunscreen" compositions) for the photoprotection of the skin and/or the hair against UV radiation, in particular solar radiation. More especially, this invention relates to novel cosmetic and/or dermatological compositions exhibiting improved photostability and including, in a cosmetically and/or dermatologically acceptable substrate (vehicle, diluent or carrier), the combination of three specific screening agents.
The present invention also relates to the use of the subject compositions in the cosmetic and/or dermatological fields.
2. Description of the Prior Art
It is known to this art that light radiation of wavelengths of from 280 nm to 400 nm permits the human epidermis to tan and that irradiation of wavelengths of from 280 nm to 320 nm, i.e., UV-B irradiation, causes erythemas and skin burns which can be harmful to the development of the natural tan; hence, this UV-B radiation must therefore be screened from the skin.
It is also known to this art that UV-A radiation, of wavelengths of from 320 nm to 400 nm, which promotes tanning of the skin, also adversely affects it, especially in the case of a sensitive skin or of a skin which is continually exposed to solar radiation. UV-A rays cause, in particular, a loss in the elasticity of the skin and the appearance of wrinkles, promoting a premature aging thereof. Such irradiation promotes triggering of the erythematous reaction or amplifies this reaction in certain individuals and may even be the source of phototoxic or photoallergic reactions. It is therefore desirable to also filter or screen out the UV-A radiation.
Thus, for purposes of ensuring protection of the skin and of the hair against all of the UV radiation which is as complete as possible and as efficacious as possible, combinations of screening agents which are active in the UV-A region and of screening agents which are active in the UV-B region are typically employed in the formulation of sunscreen compositions.
In this respect, 4-tert-butyl-4'-methoxydibenzoylmethane, marketed under the trademark "Parsol 1789" by Givaudan is a particularly advantageous screening agent active in the UV-A region, taking account of its high intrinsic absorptivity.
Similarly, 1,3,5-triazine derivatives and in particular, 2,4,6-trisp-(2'-ethylhexyl-1'-oxycarbonyl) anilino!-1,3,5-triazine, marketed under the trademark "Uvinul T 150" by BASF, have a high absorptivity for UV-B radiation. Therefore, it would be very advantageous to employ same in combination with the aforementioned 4-tert-butyl-4'-methoxydibenzoylmethane with a view towards providing products offering wide and efficacious protection throughout the entire range of UV radiation.
However, it has now been demonstrated that in the presence of 4-tert-butyl-4'-methoxydibenzoylmethane and under UV irradiation, the aforesaid 1,3,5-triazine derivatives present the disadvantage of being extensively degraded chemically. Under these conditions, the combination of the two screening agents no longer provides a prolonged broad protection of the skin and of the hair against solar radiation.